I am on my third ball of yarn for a baby blanklet, and before this I used to add a ball of yarn by tying a knot with both yarns and continuing so that I didn't have to weave anything in. With this blanket since it's going to be a gift I figured I better do it properly. So what I did was leave a pretty long tail for the old yarn and a pretty long tail for the new yarn, so I have 2 peices of yarn hanging rather than one. I did NOT tie them together but rather knit with the two peices for 3 stitches then dropped the old yarn and continued with the new. This still leaves me with 2 peices of yarn hanging from the sides. I made sure to do this at the start of a row so that they are hanging on the sides. I'm not sure if this is normal, but from the videos I have watched with ppl weaving in, I am only seeing 1 peice of yarn.

so I have a little boarder, and its in garter stitch. I am not done the blanket yet, I have just started to decrease. What the heck am I going to do with these double peices of yarn?? The yarn I am using is also very frail, it's Bernat Baby's Breath.

Well, I knot everything, but leave a little bit of a tail and weave the ends in through the nearby sts. That anchors the knot and keeps them from moving. I don't like knitting with both yarns, it's generally too bulky, but may be fine with your yarn. I'd just take the tails you have and weave them into the other sts on edge, above and below the join.

I rarely tie knots preferring to weave them in. If I have two ends together where I join I cross them and weave on opposite sides. Occasionally I put on under the other like you do before you tie a bow, but then I weave them in. Look at how they lay and weave them the way they will be the flattest. I use this method usually -

So because I have super long tails, what do you suggest cutting them too before weaving? I've never weaved either so it may be a challenge. That makes sense though that I would weave in opposite directions! Thanks for the tip on that.

Tails 6-10" long are plenty long enough. I usually leave about 6" tails so that I don't have a long thread to pull through the sts. Weave in one direction and then back and for sure the tails won't work themselves out.